1. Field of the Invention
The present invention relates to a laser processing robot system for performing laser processing using a robot.
2. Description of the Related Art
In recent years, laser processing robot systems, in which a laser irradiation device for irradiating a workpiece with a processing laser beam is attached to a distal end of a robot arm, to perform laser processing by moving the robot arm, have appeared in the market. Further, in laser processing using a laser processing robot system, a technology for performing laser processing at a predetermined position while moving a laser beam by changing the irradiation direction of the laser beam from the laser irradiation device while moving the robot arm has been known. In such a laser processing method, the distance between a workpiece and a laser irradiation device is larger than that in a conventional laser processing method. Thus, the method is sometimes referred to as “remote laser processing”. Specific examples of the processing include welding, cutting, boring, etc.
In this type of remote laser processing, a workpiece is spaced from a laser irradiation device, and accordingly, when a laser processing operation is taught to a robot, it is difficult to find out a position to be irradiated with a processing laser beam. This remarkably reduces the efficiency in a teaching operation for a robot. In general, in laser processing, it is necessary that the irradiation position of a processing laser beam precisely coincide with a processing portion of the workpiece. Thus, the difficulty of finding out the irradiation position of a processing laser beam causes reduction of the processing accuracy.
In order to solve these problems, Japanese Unexamined Patent Publication (Kokai) No. 2007-253200 discloses a method for introducing a pilot laser of visible light to the emitted welding laser beam, to cause a focal position of the welding laser beam to be easily found out. Further, Japanese Unexamined Patent Publication (Kokai) No. 2013-123743 discloses a method for detecting the position of a portion to be irradiated with a welding laser beam by an image processing device.
However, in the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2007-253200, i.e., a method for easily finding out a position to be irradiated with a welding laser beam using a pilot laser, it is necessary to additionally mount a mechanism for irradiating a workpiece with a pilot laser to a laser irradiation device. This causes the laser irradiation device to be complicated and increases cost. Further, the pilot laser is not necessary during actual producing and processing, and accordingly, the laser irradiation device has a redundant configuration.
Further, in the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2013-123743, a welding laser beam is actually emitted, and an image processing device detects a position to be irradiated with the beam. Thus, even when the brightness of a welding laser beam is reduced, or the laser irradiation device emits a low-power laser, as long as a welding laser beam is actually emitted, there is a risk that the human body, specifically, the retina may be damaged. Thus, as in the teaching of a laser processing operation to a robot, in an operation for deciding a position to be irradiated with a processing laser beam, avoiding the use of a processing laser beam to the extent possible is demanded for safety purposes.